Effects of nonsurgical myocardial reperfusion on plasma creatine kinase kinetics in man

Early predictors of late dilation and remodeling after thrombolized anterior transmural myocardial infarction

BACKGROUND AND HYPOTHESIS

Dilation of the left ventricle after myocardial infarction is associated with an adverse prognosis. There are no clinical studies on the role viable myocardium in the infarcted area assumes in relation to the development of late ventricular remodeling. The hypothesis of this study was to define the relation between remodeling and the presence of viable but akinetic myocardium in the infarct area and to identify early predictors of left ventricular (LV) dilation at 1 year.

METHODS

In all, 92 consecutive patients with myocardial infarction were divided into two groups according to their ventricular volumes. Group I included 57 patients with normal volumes at discharge (9 +/- 3 days after acute infarction) and after 12 months or with LV dilation at discharge who had a normalization of their volumes over a 12-month period. Group II included 35 patients who, independent of their initial volumes, developed LV dilation during follow-up. Low-dose dobutamine infusion was utilized at discharge for echocardiographic evaluation of contractile recovery of viable myocardial segments.

RESULTS

At the first control, patients in Group I presented an end-diastolic volume index (EDVI) of 100 +/- 7 ml/m2 which decreased to 68.8 +/- 6.5 ml/m2 12 months later (p < 0.0001), and an end-systolic volume index (ESVI) of 47.6 +/- 6.7 ml/m2 at the first control and 30.5 +/- 8.8 ml/m2 after 12 months (p < 0.001). Patients in Group II presented a mean EDVI of 116.2 +/- 8.1 ml/m2 at the first control and 138.8 +/- 8 ml/m2 12 months later (p < 0.001), and a mean ESVI of 68.8 +/- 6.5 ml/m2 at the first control and 79.5 +/- 5.4 after 12 months (p < 0.01). Ventricular mass index (VMI) in Group I increased from 106.4 +/- 11 to 122.3 +/- 15 g/m2 (p < 0.01), while in Group II it decreased from 101.1 +/- 10 to 98.7 +/- 8 g/m2 (p = NS). In Group I, mass-to-volume ratio was 1.15 +/- 0.1 g/ml at the first control and 1.67 +/- 0.1 g/ml 12 months later (p < 0.001), while in Group II it declined from 0.88 +/- 0.1 to 0.69 +/- 0.1 g/ml (p < 0.01). The multivariate analysis revealed that ejection fraction < or = 40%, restrictive filling pattern, wall motion score index > 2.5 in response to dobutamine infusion, and mass-to-volume ratio < or = 1 g/ml, all at discharge, as well as an occluded left anterior descending artery discriminate in favor of late LV dilation and remodeling.

CONCLUSIONS

Correct use of noninvasive strategies should result in early identification of postinfarct patients who are at risk of developing LV remodeling.

Prognostic significance of time-delay to peak creatine kinase after direct percutaneous coronary intervention in acute myocardial infarction patients

The aim of the present study was to investigate the prognostic significance of time-delay to peak creatine kinase (CK) after successful direct percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI). Our 240 consecutive first AMI attack subjects admitted within 5 hours from onset were successfully reperfused by direct PCI therapy. Subjects were divided into two groups according to the upper quartile value of peak-CK time from onset, the early peak-CK group (peak-CK time < or = 16 hours from onset, n = 180) and the late peak-CK group (peak-CK time > 16 hours, n = 60). (I) The early ST-segment resolution rate was lower in the late peak-CK group compared with the early peak-CK group (P < 0.05), and there were significantly fewer patients with preinfarction angina pectoris in the late peak-CK group than in the early peak-CK group (P < 0.01). (II) LVEF in the chronic stage was significantly lower in the late peak-CK group than in the early peak-CK group (49 +/- 13% versus 57 +/- 13%, P < 0.001). (III) There were significantly more patients with major complications in the late peak-CK group than in the early peak-CK group (required CABG: 10% versus 3%, P < 0.05; cardiac death: 18% versus 3%, P = 0.0001). (IV) Multivariate analysis identified late peak-CK as an independent predictor of cardiac death (Odds ratio 7.91, 95% C.I. 1.40-44.11, P < 0.05). In patients with AMI, the time-delay to peak-CK after successful direct PCI may be closely related to left-ventricular systolic dysfunction and poor patient outcome, including mortality.

Early peak creatine kinase activity is not always a marker of successful reperfusion with myocardial salvage in patients with reperfused anterior acute myocardial infarction

BACKGROUND

Although early peak creatine kinase activity (peak CK) is considered a reliable marker of coronary reperfusion in patients with acute myocardial infarction (AMI), whether early peak CK indicates good myocardial salvage is unclear. Moreover, some patients have late peak CK despite successful reperfusion, and its clinical implication remains to be elucidated.

METHODS AND RESULTS

We examined the association of the time to peak CK with predischarge left ventricular function in 124 patients with a first AMI who had successful reperfusion within 6 hours from symptom onset. Patients were classified according to the time from reperfusion to peak CK: group A, 61 patients with peak CK < 6 hours; group B, 42 with peak CK from 6 to 12 hours; and group C, 21 with peak CK > 12 hours. There were no differences among the 3 groups in age, sex, method of reperfusion, time from symptom onset to reperfusion, collateral circulation, or the extent of risk area estimated by number of leads with ST-segment elevation. Left ventricular ejection fraction measured by predischarge left ventriculography was lowest in group A, followed by group B, and highest in group C (median values, 43%, 52%, and 60%, P < .01). Left ventricular dysfunction (left ventricular ejection fraction < or = 40%) occurred in 26 (43%) patients in group A, 8 (19%) in group B, and none in group C (P < .01).

CONCLUSIONS

We conclude that compared with early peak CK, late peak CK consistently reflects good myocardial salvage in patients with anterior AMI who had successful reperfusion within 6 hours from symptom onset.

Aldosterone inhibition limits collagen synthesis and progressive left ventricular enlargement after anterior myocardial infarction

BACKGROUND

The reparative process after myocardial infarction is related to active collagen synthesis. Previous experimental studies demonstrated that cardiac fibrosis is mediated by angiotensin II and aldosterone; this mechanism is not clearly confirmed in patients who have had a myocardial infarction. The aim of this study was to evaluate whether the suppression of aldosterone may be helpful in reducing postinfarction collagen synthesis (and progressive left ventricular dilation) in patients treated with an angiotensin-converting enzyme inhibitor for a recent myocardial infarction.

METHODS

We enrolled 46 patients (ages 60+/-11 years, 34 males) with a first episode of anterior transmural thrombolized myocardial infarction. At hospital discharge patients were randomized to receive potassium canrenoate, an oral aldosterone inhibitor, 50 mg once daily (group 1, n = 24) or placebo (group 2, n = 22). All enrolled patients were on angiotensin-converting enzyme inhibitor therapy. The serum concentration of the aminoterminal propeptide of type III procollagen was used to measure the collagen synthesis rate; dosage was obtained before enrollment, at hospital discharge, and after 3, 6, and 12 months of follow-up.

RESULTS

After 3, 6, and 12 months of treatment, the aminoterminal propeptide of type III procollagen serum levels was significantly higher in the placebo group compared with the aldosterone inhibitor group; after 6 and 12 months we observed significantly smaller left ventricular volumes in the active treatment group.

CONCLUSION

Potassium canrenoate, combined with an angiotensin-converting enzyme inhibitor, may reduce postinfarction collagen synthesis and progressive left ventricular dilation.

Troponin T as a Marker of Infarction during Coronary Bypass Surgery

To evaluate serum troponin T as a marker of perioperative myocardial infarction, 50 patients undergoing coronary artery bypass grafting were divided into 2 groups. Group A (14 patients) had serum creatine kinase MB-isoenzyme levels above 100 U·L−1and electrocardiographic changes indicative of infarction. Group B (36 patients) had creatine kinase MB levels below 100 U·L−1and no electrocardiographic changes. Blood samples were obtained preoperatively, 6 hours after aortic declamping, and on postoperative day 1, 2, and 3. Following surgery, all patients had increased levels of troponin T and creatine kinase MB. Troponin T was significantly higher in group A compared to group B at 6 hours, day 1, and day 2 postoperatively. Creatine kinase MB levels were significantly higher in group A compared to group B at 6 hours and day 1 postoperatively. The increased levels of troponin T in patients without myocardial infarction suggest that some operative myocardial damage occurred. Patients with perioperative myocardial infarction had significantly higher levels of troponin T up to postoperative day 2, whereas creatine kinase MB levels were almost normal by day 2. This suggests that troponin T may be used up to 2 days postoperatively for detection of myocardial infarction.

Plasma vasoactive peptides after acute myocardial infarction in relation to left ventricular dysfunction

We measured plasma concentrations of vasoactive peptides in 32 patients with acute myocardial infarction and evaluated their value as markers of left ventricular dysfunction. Plasma levels of atrial natriuretic peptide (ANP), the N-terminal fragment of proANP (NT-proANP), B-type natriuretic peptide (BNP) and endothelin-1 were measured serially by radioimmunoassays. The infarct size was estimated from the creatine kinase MB release curve. Coronary angiography and left ventricular cineangiography were performed in all patients during hospitalization and 6 months later in 15 patients. Myocardial infarction caused an increase in vasoactive peptides, the highest values for ANP (36.5+/-6.79 pmol/l), NT-proANP (1130+/-170 pmol/l) and endothelin-1 (9.72+/-0.68 pmol/l) being found on admission and those for BNP (56.0+/-7.13 pmol/l) on Day 2. Plasma levels of natriuretic peptides were dependent on infarct size, its location and degree of myocardial dysfunction and that of BNP also on infarct artery patency. Plasma endothelin-1 level was higher in patients with TIMI 3 than TIMI 0-2 flow. Plasma vasoactive peptides remained elevated during the 6-month follow-up period and they were dependent on the degree of myocardial dysfunction. BNP measured on any day of hospitalization showed the best correlation with ejection fraction measured during the acute phase of infarction or at 6 months. The results show that BNP is the best indicator of left ventricular dysfunction after myocardial infarction and its reliability is not dependent on the time point of measurement.

The distinction between coronary and myocardial reperfusion after thrombolytic therapy by clinical markers of reperfusion

OBJECTIVES

We sought to examine the hypothesis that rapid resolution of ST-segment elevation in acute myocardial infarction (AMI) patients with early peak creatine kinase (CK) after thrombolytic therapy differentiates among patients with early recanalization between those with and those without adequate tissue (myocardial) reperfusion.

BACKGROUND

Early recanalization of the epicardial infarct-related artery (IRA) during AMI does not ensure adequate reperfusion on the myocardial level. While early peak CK after thrombolysis results from early and abrupt restoration of the coronary flow to the infarcted area, rapid ST-segment resolution, which is another clinical marker of successful reperfusion, reflects changes of the myocardial tissue itself.

METHODS

We compared the clinical and the angiographic results of 162 AMI patients with early peak CK (< or =12 h) after thrombolytic therapy with (group A) and without (group B) concomitant rapid resolution of ST-segment elevation.

RESULTS

Patients in groups A and B had similar patency rates of the IRA on angiography (anterior infarction: 93% vs. 93%; inferior infarction: 89% vs. 77%). Nevertheless, group A versus B patients had lower peak CK (anterior infarction: 1,083+/-585 IU/ml vs. 1,950+/-1,216, p < 0.01; and inferior infarction: 940+/-750 IU/ml vs. 1,350+/-820, p=0.18) and better left ventricular ejection fraction (anterior infarction: 49+/-8, vs. 44+/-8, p < 0.01; inferior infarction: 56+/-12 vs. 51+/-10, p=0.1). In a 2-year follow-up, group A as compared with group B patients had a lower rate of congestive heart failure (1% vs. 13%, p < 0.01) and mortality (2% vs. 13%, p < 0.01).

CONCLUSIONS

Among patients in whom reperfusion appears to have taken place using an early peak CK as a marker, the coexistence of rapid resolution of ST-segment elevation further differentiates among patients with an opened culprit artery between the ones with and without adequate myocardial reperfusion.

Modification in serum concentrations of aminoterminal propeptide of type III procollagen in patients with previous transmural myocardial infarction

The aim of our study was to evaluate the modification of serum concentration of aminoterminal propeptide of type III procollagen (PIIINP) in 70 patients with previous transmural myocardial infarction. In 38 patients (group 1 ) PIIINP levels increased at 6 and 12 months after infarction; in 32 patients (group 2) PIIINP increased at 6 months, returning to baseline at 12 months. At the same time we observed a significant left ventricular enlargement and worsening of the performance in group 1, whereas in group 2 an improvement was seen in left ventricular volumes and performance. In conclusion, rearrangement of collagen myocardial matrix plays an important role in left ventricular postinfarction modification. This process can be easily followed over time in a noninvasive manner by dosing serum PIIINP concentrations.

Collagen scar formation after acute myocardial infarction: relationships to infarct size, left ventricular function, and coronary artery patency

BACKGROUND

Left ventricular function after acute myocardial infarction (AMI) is determined by the expansion of the infarct zone and remodeling of the noninfarcted myocardium. An occluded infarct-related artery (IRA) is an independent risk factor for remodeling.

METHODS AND RESULTS

Changes in myocardial collagen metabolism were evaluated in 36 patients with suspected AMI. The plasma creatine kinase MB fraction and myoglobin release curves were analyzed for assessment of early reperfusion and infarct size. Collagen scar formation was evaluated by measurement of serum concentrations of the aminoterminal propeptide of type III procollagen (PIIINP), the aminoterminal propeptide of type I procollagen (intact PINP), and the carboxyterminal propeptide of type I procollagen (PICP). Plasma renin activity and urine excretion of cortisol and aldosterone were also measured. Coronary angiography and left ventricular cineangiography were performed during early hospitalization. The serum concentration of PIIINP increased from 3.50+/-0.20 to a maximum of 5.08+/-0.36 microg/L (n=32) in the patients with AMI, whereas the concentrations of intact PINP and PICP tended to decrease. The area under the curve (AUC) of PIIINP during the first 10 postinfarction days was larger in patients with severe heart failure or ejection fractions < or = 40% than in those with no heart failure or with an ejection fraction > 40% (P<.05 and P<.01, respectively), and it was also larger in the patients with TIMI grade 0 to 2 flows than in those with TIMI 3 flows (P<.05), despite similar enzymatically determined infarct sizes. No significant correlations between PIIINP and neurohumoral parameters were observed. The AUC of PIIINP and the change in PIIINP during the first 4 days were significantly correlated with indices of cardiac function.

CONCLUSIONS

Collagen scar formation after AMI can be quantified by measurement of serum PIIINP concentrations. Scar formation is more prominent in large infarctions causing left ventricular dysfunction and in patients with occluded IRAs.

Cardiac troponin T immunoassay on biotin--streptavidin-coated microplates: preliminary performance in acute myocardial infarction

We have adapted the cardiac troponin T (TnT) immunoassay system (ELISA troponin T, Boehringer Mannheim, Germany), which is based upon streptavidin-biotin immunoassay technology, to a sensitive microplate system. A coating of microplates with biotinylated bovine serum albumin (biotin-LC-BSA) remained stable for months. A secondary streptavidin coating was prepared as the first step of the assay. By using o-phenylenediamine (o-PD) as a substrate for the peroxidase-anti-TnT conjugate, the system allowed rapid kinetic measurement of TnT levels. The upper limit of a reference population (97.5th percentile) was found to be 0.04 mu g l-1. Intra-assay imprecision at 0.08 mu g l-1 was 8%, and 3-4% between 0.28 and 4 mu g l-1. Between-assay imprecision was 6.2% at 0.28 mu g l-1. Studies of TnT and CK-MB mass concentration in acute myocardial infarction patients, treated with streptokinase, demonstrated a clinical sensitivity of the TnT microplate system similar to that of the CK-MB mass concentration test, during the first 8 h after initiation of thrombolytic therapy, at discriminator levels of 0.1 mu g l-1 (TnT) and 8 mu g l-1 (CK-MB mass concentration). The early CK-MB/TnT ratio was lower in patients with signs of successful reperfusion (early peak CK-MB) than in the remaining patients (p<0.001). Serum samples from two patients with renal failure and one patient with rhabdomyolysis demonstrated strong non-linear behaviour with dilution, indicating the presence of an interfering factor. Kinetic measurement compared favourably with end-point analysis with respect to sensitivity and total analysis time. The system described greatly reduces the costs of TnT measurements compared to the ES systems. The total assay time is 70-90 min.

Early assessment of reperfusion therapy using cardiac troponin T

OBJECTIVES

The purpose of this study was to investigate the utility of cardiac troponin T for early assessment of reperfusion therapy.

BACKGROUND

Several biochemical markers are used for early noninvasive detection of reperfusion during intravenous thrombolytic therapy. However, cardiac troponin T, a new myocardial-specific marker, has not been used previously for this purpose.

METHODS

We measured troponin T and creatine kinase, MB isoenzyme (CK-MB) levels in 38 patients with acute myocardial infarction whose infarct-related artery was totally occluded before reperfusion therapy. Subjects comprised 14 patients with successful angioplasty (group 1), 12 patients with successful thrombolytic therapy (group 2) and 12 patients with unsuccessful attempted reperfusion (group 3). Blood samples were taken every 15 min, and coronary angiography was performed every 5 to 8 min until 60 min after reperfusion (groups 1 and 2) or after the initiation of treatment (group 3). We calculated the increase in troponin T (delta troponin T) and CK-MB (delta CK-MB) 60 min after treatment was initiated and 60 min after reperfusion in groups 1 and 2.

RESULTS

Mean (+/- SD) delta troponin T and delta CK-MB levels were 9.35 +/- 7.83 ng/ml and 125 +/- 83 mU/ml in group 1 and 3.23 +/- 3.08 ng/ml and 130 +/- 137 mU/ml in group 2, respectively, 60 min after treatment and were 10.1 +/- 8.35 ng/ml and 131 +/- 84 mU/ml in group 1 and 6.84 +/- 8.30 ng/ml and 158 +/- 146 mU/ml in group 2, respectively, 60 min after reperfusion. These values were significantly higher than those 60 min after treatment in group 3: 0.16 +/- 0.19 ng/ml and 10 +/- 9 mU/ml, respectively. The predictive accuracy for detecting reperfusion using a threshold value of 0.50 ng/ml of delta troponin T and 25 mU/ml of delta CK-MB was 100% in group 1 and 92% in group 2 60 min after treatment, respectively. There was significant correlation between delta troponin T and delta CK-MB.

CONCLUSIONS

Serial measurements of cardiac troponin T as well as of CK-MB are useful for early assessment of reperfusion therapy.

Rapid diagnosis of coronary reperfusion by measurement of myoglobin level every 15 min in acute myocardial infarction

OBJECTIVES

The purpose of this study was to examine whether coronary reperfusion can be diagnosed rapidly and accurately by myoglobin measurements.

BACKGROUND

When intravenous thrombolysis is used for acute myocardial infarction, it is important to determine coronary reperfusion rapidly and noninvasively so that further treatment can be initiated.

METHODS

We determined myoglobin, creatine kinase (CK) and creatine kinase, MB fraction (CK-MB) isoenzyme levels in 63 patients with acute myocardial infarction with total occlusion of the infarct-related artery that was confirmed by coronary angiography. Myoglobin was measured by turbidimetric latex agglutination, which has an assay time of 10 min. We measured myoglobin, CK and CK-MB every 15 min in 45 patients with and 18 patients without reperfusion. The condition of the infarct-related artery was confirmed every 5 to 8 min by coronary angiography.

RESULTS

The rate of increase in myoglobin, CK, and CK-MB at 15, 30, 45 and 60 min after treatment and reperfusion was significantly higher in the reperfused than in the nonreperfused group. In the reperfused group, the rate of increase in myoglobin was significantly higher than the corresponding rate of increase in CK and CK-MB at 15, 30 and 45 min after reperfusion. When reperfusion was evaluated on the basis of a cutoff level (myoglobin > or = 2.0, CK > or = 1.8, CK-MB > or = 1.5), the predictive accuracy of myoglobin (95%) was significantly higher than that of CK (68%) and CK-MB (73%) at 15 min after reperfusion.

CONCLUSIONS

Coronary reperfusion can be rapidly and accurately detected by measurement of the plasma myoglobin every 15 min.

Detection of reperfusion 30 and 60 minutes after coronary recanalization by a rapid new assay of creatine kinase isoforms in acute myocardial infarction

We measured creatine kinase (CK) isoforms by a new immunoinhibition method to evaluate their usefulness in detecting early coronary reperfusion. Blood samples were collected at 15-minute intervals from 50 patients with acute myocardial infarction. CK isoforms were determined by a 10-minute immunoinhibition method with an autoanalyzer. Values for inhibited isoforms (MM3, MM2/2, and MB2/2) were divided by those of noninhibited isoforms (MM1, MM2/2, MB1, MB2/2, and BB) to calculate the isoform ratio. In the reperfused group the increase in the isoform ratio was 2.69 +/- 1.80 (SD) 30 minutes after reperfusion and 2.41 +/- 2.01 at 60 minutes, which was significantly higher than the corresponding values in the nonreperfused group (0.17 +/- 0.16 and 0.32 +/- 0.26, respectively). When an increase of 0.70 or more in the isoform ratio was used as the criterion for reperfusion, the sensitivity and specificity were 92% and 100% at 30 minutes and 100% and 100% at 60 minutes after recanalization, respectively. We conclude that the isoform ratio obtained by the new 10-minute assay of CK isoforms is useful for the noninvasive detection of reperfusion 30 and 60 minutes after recanalization in acute myocardial infarction.

Early detection of coronary reperfusion by rapid assessment of plasma myoglobin

We assayed plasma myoglobin and creatine kinase to elucidate the usefulness of rapid assessment of myoglobin for detecting coronary reperfusion in 31 patients with acute myocardial infarction. Reperfusion was achieved in 20 patients by thrombolytic therapy or angioplasty, and it was not in 11 patients. Blood sampling was performed before and 43 +/- 15 (+/- SD) min after the start of treatment. In the reperfused group, blood samples were obtained before and 26 +/- 10 min after reperfusion. Myoglobin was assayed by a new quantitative test based on latex agglutination turbidimetry which required an assay time of 10 min. After treatment, the rate of increase of plasma myoglobin was significantly higher than that of plasma creatine kinase in the reperfused group (9.7 +/- 9.5 and 2.8 +/- 1.6-fold), but not in the occluded group (1.8 +/- 0.6 and 1.5 +/- 0.3-fold). When a 3.0-fold or greater increase in myoglobin (1.9-fold or greater increase in creatine kinase) was taken as evidence of coronary reperfusion, the sensitivity and specificity were 95% and 100% (70% and 82% in creatine kinase), respectively. In conclusion, using the rate of increase of myoglobin, as measured by latex agglutination turbidimetry, coronary reperfusion can be diagnosed within 1 h after reperfusion.

Calcitonin gene-related peptide in patients with and without early reperfusion after acute myocardial infarction

Plasma concentrations of calcitonin gene-related peptide (CGRP), a potent regulator of vascular tone, creatine kinase, myoglobin, and cardiac troponin T were assessed in 31 patients with acute myocardial infarction. In patients who had sustained acute myocardial infarctions, maximum CGRP concentrations (median, 3.2 pmol/L; interquartile range, 1.5 to 4.8 pmol/L) were markedly elevated as compared with healthy control subjects (n = 23; median, 1.02 pmol/L; p = 0.02). However, no marked differences in CGRP levels were observed between patients with early reperfusion (n = 19; median, 3.5 pmol/L) and patients without early reperfusion (n = 12; median, 2.6 pmol/L; p = 0.96), as well as between those with congestive heart failure (n = 8; median, 3.9 pmol/L) and those without congestive heart failure (n = 23; median, 3.2 pmol/L; p = 0.62). CGRP did not correlate closely with myocardial protein release or hemodynamic parameters (heart rate and blood pressure) or the occurrence of arrhythmias. Therefore we conclude that elevated peripheral venous CGRP concentrations in patients who have sustained an acute myocardial infarction are independent of successful reperfusion and hemodynamic state. Although the cause of CGRP increase is not yet identified, CGRP may play a role in the regulation of coronary vascular tone in patients after acute myocardial infarction.

Early diagnosis of acute myocardial infarction by a newly developed rapid immunoturbidimetric assay for myoglobin

OBJECTIVE

To evaluate a rapid immunoturbidimetric assay for myoglobin and to investigate its clinical usefulness in the early detection of acute myocardial infarction.

DESIGN

Prospective study. Immunoturbidimetrically determined myoglobin concentrations were compared with radioimmunoassay results obtained with the same blood samples. The diagnostic performance of myoglobin determination was compared with creatine kinase and creatine kinase MB activity (current standard of routine diagnosis).

SETTINGS

Part 1: coronary care unit. Part 2: emergency room in a university hospital.

PATIENTS

Part 1:30 patients with acute myocardial infarction admitted not later than four hours (median two hours) after the onset of symptoms. Part 2: 126 patients admitted to the emergency room with chest pain not caused by trauma (51 cases of acute myocardial infarction, 51 cases of angina pectoris, and 24 cases of chest pain not related to coronary artery disease).

INTERVENTIONS

Part 1: routine treatment including intravenous thrombolytic treatment (28 patients). Part 2: routine emergency treatment without thrombolytic treatment.

MAIN OUTCOME MEASURES

The analytical quality of the immunoturbidimetric myoglobin assay and a comparison between the myoglobin assay and creatine kinase and creatine kinase MB for diagnostic sensitivity and performance.

RESULTS

The immunoturbidimetric myoglobin assay was fast and convenient and gave myoglobin determinations of high analytical quality. The concentration of myoglobin increased, peaked, and returned to the reference range significantly earlier than creatine kinase (p < or = 0.0001) and creatine kinase MB (p < or = 0.0002). Before thrombolytic therapy was started the diagnostic sensitivity of myoglobin was significantly higher than that of creatine kinase MB activity 0-6 h after the onset of chest pain and significantly higher (0.82 v 0.29) than creatine kinase 2-4 h after the onset of chest pain. In almost all patients (92%) plasma myoglobin concentrations were increased 4-6 h after the onset of chest pain.

CONCLUSION

Myoglobin was more sensitive in detecting early myocardial infarction than creatine kinase and creatine kinase MB activity. Immunoturbidimetric myoglobin measurements could be useful in the early evaluation of patients with suspected myocardial infarction because this assay takes less than two minutes.

Are enzymatic tests good indicators of coronary reperfusion?

OBJECTIVE

To assess the accuracy of four enzymatic tests, including early release rates of creatine kinase and alpha-hydroxybutyrate dehydrogenase, in assessing coronary reperfusion after thrombolytic therapy.

DESIGN

A prospective clinical trial identifying patients with a successful thrombolytic treatment.

PATIENTS

Eighty nine patients with acute myocardial infarction were studied. Arteriography showed a closed infarct related artery in all of them. Reperfusion due to thrombolysis occurred in 74 patients and there was no reperfusion in 15 patients.

RESULTS

The 74 patients showing coronary reperfusion had a significantly shorter time to peak creatine kinase activity, higher early release rates for creatine kinase and alpha-hydroxybutyrate dehydrogenase, and a more rapid release of alpha-hydroxybutyrate dehydrogenase (ratio of cumulative release of alpha-hydroxybutyrate dehydrogenase during the first 24 hours to that 72 hours after infarction). All these differences were statistically significant (p less than 0.001). Optimum cut off levels were determined with decision level plots and the accuracy of the four enzymatic tests was calculated. Accuracy was low for all four tests (73%, 70%, 70%, and 82%).

CONCLUSION

None of the four enzymatic tests accurately predicted the perfusion state of the infarct related coronary artery after thrombolysis. These tests cannot be used reliably in routine clinical practice as non-angiographic markers of coronary reperfusion.

Early detection of acute myocardial infarction by measurement of mass concentration of creatine kinase-MB

The diagnostic sensitivity and performance of immunoenzymometric measurements of creatine kinase (CK)-MB mass concentrations in the early diagnosis of acute myocardial infarction (AMI) were examined and compared with the sensitivities and performances of CK and CK-MB activity, in the context of simultaneous measurements of CK, CK-MB activity, and CK-MB mass concentrations in serially drawn blood samples obtained immediately from 36 patients with AMI and 126 patients with chest pain on admission to the emergency room of the department of internal medicine. In the 36 patients with AMI, who were all admitted no later than 4 hours after the onset of chest pain, pathologic increase occurred significantly earlier in CK-MB mass than in both CK and CK-MB activity, with a median difference of 1 hour each. In patients coming to the emergency room (51 with AMI, 51 with angina pectoris and 24 with chest pain not related to coronary artery disease), CK-MB mass was the best diagnostic measurement for AMI of all markers tested (significantly higher efficiency, Youden index and likelihood ratio than both CK and CK-MB activity). Before initiating thrombolytic therapy, the sensitivity of CK-MB mass is significantly higher than CK-MB activity during the 0- to 6-hour period and significantly higher than CK activity during the 2- to 4-hour period after the onset of chest pain. Consequently, it is often possible to diagnose an AMI on the basis of increased CK-MB mass concentrations even at a time when CK and CK-MB activities are still within the reference interval.

Electrophoresis of serum isoenzymes and proteins following acute myocardial infarction

The clinical significance of the serum enzymes creatine kinase (CK, EC 2.7.3.2), lactate dehydrogenase (LD, EC 1.1.1.27) and aspartate aminotransferase (EC 2.6.1.1), and the isoenzymes CK 1-3 and LD 1-5, in acute myocardial infarction (AMI) is reviewed. Particular attention is given to electrophoretic analysis of the isoenzymes (and the CK isoforms/subforms) following AMI and thrombolytic therapy. Other protein markers for the monitoring of AMI, including myoglobin and muscle contractile proteins, are also discussed and the potential for the detection of new marker proteins using high-resolution two-dimensional electrophoretic methods is demonstrated. Whilst emphasis is placed upon electrophoretic methods the value of complementary immunoassays is acknowledged in order to maintain a balanced perspective.

Thrombolytic therapy with streptokinase stimulates collagen breakdown

BACKGROUND

Plasmin is capable of degrading extracellular matrix components such as collagen in vitro. To evaluate the significance of this for in vivo conditions, we set out to study the effect of streptokinase, which acts by converting plasminogen to plasmin, on the serum concentrations of the amino-terminal propeptide of type III procollagen (PIIINP) and the carboxy-terminal propeptide of type I procollagen (PICP).

METHODS AND RESULTS

Twenty-three patients with suspected acute myocardial infarction were included in the study; 17 of them received thrombolytic therapy, and six were treated conservatively. PIIINP and PICP were assayed with radioimmunoassays. Kinetics of creatine kinase-MB release were determined to differentiate reperfusers from nonreperfusers. Composite curves of creatine kinase-MB release were constructed for different patient subgroups. During streptokinase infusion the serum concentrations of PIIINP increased rapidly, with a maximum mean increase of 50% (from 2.2 +/- 0.2 to 3.3 +/- 0.3 micrograms/l) in 45 minutes. A similar increase was also observed in two patients who received thrombolytic therapy but did not subsequently develop any myocardial infarction determined on the basis of enzyme release. The relative increase in PIIINP during streptokinase treatment was higher in those acute myocardial infarction patients with probable reperfusion than those with nonprobable reperfusion. Corresponding changes in PIIINP were not seen in the control group. Two days later there was a second increase in serum PIIINP for both patient groups. This change coincided with a similar increase in PICP.

CONCLUSIONS

We conclude that streptokinase, probably by activation of plasminogen to plasmin, stimulates the breakdown of type III collagen during thrombolytic therapy. This phenomenon may decrease the risk of rethrombosis of the affected artery if the exposed collagen is responsible for thrombosis formation, but it could also be involved in the development of hemorrhagic complications during thrombolytic therapy. The second increase in PIIINP levels probably indicates type III collagen synthesis of the infarcted area. This investigation represents a pilot study, and more studies on the effects of various thrombolytic agents on interstitial collagen metabolism are obviously needed.

French multicenter trial of anistreplase versus heparin in acute myocardial infarction

Eighty-four patients aged less than 71 years with less than 4-hour duration acute myocardial infarction (AMI) were randomized in a multicenter study to 30 U anistreplase or heparin (single injection of 6500 IU followed by 1000 IU/hr). Early reperfusion was assessed from ECG changes (50% of sum ST decrease 2 hours postdosing) and the CK release profile (CK peak less than 16 hours after onset of symptoms, CK slope greater than 10%/hr). Reperfusion rates in patients meeting at least two criteria of reperfusion were 62.5% on anistreplase versus 27.5% on heparin. On delayed angiogram (13.7 +/- 3.4 days), patency rates were 66% with anistreplase versus 47% (NS) with heparin in 76 patients. Global LVF was similar in both groups. With anistreplase, the mean lowest fibrinogen level was 0.43 +/- 0.55 g/l, plasminogen was 20 +/- 9%, and the highest F.D.P. was 1447 +/- 548 micrograms/ml. All values recovered by hour 48. In-hospital and 1-year follow-up mortality was 7.2% (three patients) with anistreplase versus 10.2% (four patients) with heparin. Bleeding occurred in 9.7% and 5.1% of the patients (NS), respectively. No intracranial hemorrhage occurred. Thus, with combined clinical criteria or reperfusion, anistreplase is twice as efficient as heparin, has a good tolerance, and is easy to use as a single injection.

Optimal criteria for rapid detection of myocardial reperfusion by creatine kinase MM isoforms in the presence of residual high grade coronary stenosis

Analysis of isoforms of MM creatine kinase (CK) in plasma is being developed as a means for rapid detection of coronary recanalization in patients given thrombolytic agents. To determine whether flow-limiting residual stenosis typical of that seen in patients affects plasma isoform profiles, stenosis sufficient to preclude reactive hyperemia was induced in dogs before coronary occlusion, followed by recanalization in 2 h. Plasma activities of the MM CK isoform released from myocardium (MM3) and its two conversion products elaborated sequentially (MM2 and MM1) were assayed in serial samples with a rapid quantitative chromatofocusing procedure. Reperfusion in 10 dogs shortened the mean intervals (+/-SD) to the occurrence of peak MM3 activity (3.7 +/- 0.9 h), peak MM3 expressed as a percent of total CK activity (MM3%, 2.5 +/- 0.3 h) and the maximal ratio of MM3 to MM1 (2.7 +/- 0.3 h) compared with results in 10 control dogs without reperfusion. Nevertheless, the appearance of these peaks was delayed by 8% to 57% when residual stenosis was present. In contrast, the rate of increase of MM3% was delineated before the peak, was fivefold greater with recanalization (1.19 +/- 0.46 versus 0.26 +/- 0.11% min-1 in control dogs) and was not attenuated by residual stenosis. Thus, this criterion appears capable of delineating recanalization early after thrombolysis whether or not high grade residual stenosis is present.

Quantification of myocardial infarct size after coronary reperfusion by serum cardiac myosin light chain II in conscious dogs

The effects of early coronary artery reperfusion on the relation between the extent of myocardial infarction and serum levels of cardiac myosin light chain II or plasma creatine kinase levels were evaluated in the conscious dog. Hydraulic occluders were placed on the left anterior descending arteries of 38 dogs. Seven to 10 days later, myocardial infarction was produced. Coronary reperfusion was performed 3 hours (group A1, n = 13) and 6 hours (group A2, n = 12) after the occlusion. In the other 13 dogs, coronary occlusion was sustained throughout the course of the experiment (group B). Seven days after the occlusion, the heart was cut from the apex to the base into 4-mm slices, and infarct size was determined macroscopically. Rapid appearance and early peaking of creatine kinase were observed in group A. Cumulative release of creatine kinase significantly correlated with infarct size in group A (infarct size ranged from 0.1 to 20.1 g, r = 0.90) and group B (from 0.6 to 26.8 g, r = 0.91). However, since creatine kinase release in group A was greater in comparison with that from infarcts of the same size in group B, the slope of the regression line for group A was significantly steeper (p less than 0.05). Cardiac myosin light chain II appeared as early as creatine kinase did and continued to be elevated for 7 days. A very close relation was observed between infarct size and total cardiac myosin light chain II release (r = 0.87 for group A, and r = 0.88 for group B) or peak level of light chain II (r = 0.85 for group A, and r = 0.81 for group B). In addition, the slopes of the regression lines for infarct size and both peak and total release of light chain II did not differ between group A and group B. On histological examination, viable myocardium was frequently observed in the epicardium of the ischemic area in group A1; therefore, infarct size was greater in group B than in group A1 (p less than 0.05). Also, myocardial creatine kinase content in the epicardium of the center of the ischemic area in group A1 was greater than that in group B. Cardiac myosin light chain II release in group A1 was less than that in group B, whereas no difference was found in plasma creatine kinase release among groups A1, A2, and B.(ABSTRACT TRUNCATED AT 250 WORDS)

Enzymatic estimation of the extent of irreversible myocardial injury early after reperfusion

To determine whether the extent of infarction can be estimated enzymatically soon after reperfusion, the rate of increase of creatine kinase (CK) activity in plasma early after coronary recanalization was compared with infarct size in 18 dogs and 10 patients. In dogs, reperfusion was initiated 2 to 4 hours after coronary occlusion. CK activity was measured in serial plasma samples and infarct size was assessed histochemically at 24 hours. A substantial and consistent fraction of the total CK appearing in plasma over 24 hours (cumulative CK) appeared in plasma soon after reperfusion, i.e., 21 +/- 2% (SE) within 30 minutes and 38 +/- 3% within 1 hour. The rate of increase of plasma CK activity correlated closely with infarct size when CK release was measured during the first 30 minutes (r = 0.92) or 60 minutes (r = 0.92) after reperfusion (n = 18). Similarly, in patients the rate of increase of CK activity measured within 2.5 hours of the time of reperfusion was closely related to infarct size delineated by positron emission tomography 1 to 2 weeks later (r = 0.93). Thus the rate of appearance of CK in plasma early after reperfusion reflects the extent of irreversible injury ultimately sustained and provides a criterion likely to be useful for prospective identification of patients at high risk after coronary recanalization.

Early noninvasive detection of successful reperfusion in patients with acute myocardial infarction

Myoglobin (Mb) is a protein that enters rapidly and is rapidly cleared from plasma after coronary reperfusion. We sought to determine the accuracy with which a rapid rise in plasma [Mb] could predict successful coronary artery reopening in patients undergoing coronary arteriography in conjunction with attempted reperfusion in acute myocardial infarction. In 42 patients, plasma Mb levels were measured before and for at least 4 hours after attempted reperfusion. Thirty-five patients were successfully reperfused. In each, the plasma Mb level rose rapidly with peak [Mb] occurring at 111 +/- 8.1 (+/- SEM) minutes after application of therapy. In contrast, Mb levels rose more slowly in the seven patients who were not reperfused, with peak [Mb] occurring 360 +/- 61.4 minutes after attempted reperfusion. T25-100 (the time required for [Mb] to rise from 25% to 100% of peak value) was shorter in patients successfully reperfused (71 +/- 7.9 minutes) and longer (341 +/- 35.3 minutes) in patients in whom therapy was unsuccessful. A rapid rise in [Mb] after successful reperfusion was also evident by a more than 4.6-fold rise in [Mb] over the first 2 hours after reperfusion in all but five patients; in contrast, [Mb] rose by less than 4.6-fold over this same interval in every patient not successfully reperfused (sensitivity, 85%; specificity, 100%; predictive accuracy, 88%). We conclude that a rapid rise in plasma Mb level over the initial 2 hours after attempted reperfusion in acute myocardial infarction provides a useful index of successful reperfusion.

Prognostic significance of an early rise to peak creatine kinase after acute myocardial infarction

Because an early rise to peak creatine kinase (CK) is regarded as a noninvasive marker of early coronary reperfusion, the short- and long-term significance of this phenomenon was studied. In a series of consecutive patients admitted between 1974 and 1976 with acute myocardial infarction (AMI), 2 hourly CK estimations were performed. Complete CK curves were obtained in 102 patients, all of whom have been followed for 10 years. Without reference to their clinical course or follow-up, patients were divided into those with CK curves peaking less than or equal to 15 hours (mean 11 hours; n = 41) and those with curves peaking greater than 15 hours (mean 21 hours; n = 61). There were no differences in age, Norris index, location of AMI or past history of coronary artery disease between the groups; however, the mean peak CK was higher in the late peak group (p less than 0.05) and there were more non-Q-wave infarcts in the early peak group (p less than 0.01). In the first 9 months of follow-up there were fewer cardiac deaths in the early peak group (5 vs 13%), but this difference was not significant, and at 12 months the survival curves crossed. At 10 years, survival was 42% in the early peak group and 65% in the late peak group (p less than 0.05). Cox regression analysis showed that early peaking of the CK curve was an independent marker for cardiac death overall (relative risk 2.3, p less than 0.02). In 1-year survivors the relative risk increased to 3.8 (p less than 0.008).(ABSTRACT TRUNCATED AT 250 WORDS)

Rapid enzyme release from acutely infarcted myocardium after early thrombolytic therapy: washout or reperfusion damage?

In a randomized study on early intracoronary thrombolytic therapy in patients with acute myocardial infarction (AMI), serial plasma enzyme activities were measured to analyze the rate of enzyme appearance in plasma with reference to treatment allocation, area at risk, and infarct size. Cumulative activities of alpha-hydroxybutyrate dehydrogenase (HBDH) appearing in plasma in the first 24 hours (Q24), 48 hours (Q48), and 72 hours (Q72) were calculated to obtain infarct size (= Q72) and rate of HBDH appearance in plasma (= Q24/Q72). Analyzed on the basis of "intention to treat" in 448 patients with AMI, the mean Q24/Q72 value (+/- SEM) was 0.653 +/- 0.011 in 230 patients receiving thrombolytic therapy; this value was significantly (p less than 0.001) higher than that observed in 218 patients receiving conventional therapy (0.504 +/- 0.012). In the thrombolysis group Q24/Q72 was independent of infarct size, whereas in the control group Q24/Q72 was negatively correlated with infarct size (r = -0.26; p less than 0.001). Plotted against the sum of ST segment elevations at admission (sigma ST) mean Q24 values were similar in both treatment groups, but mean Q48 and especially Q72 values were larger in the control group than in the thrombolysis group. We conclude that: (1) in reperfused infarctions the time course for development of infarct is accelerated in comparison to unreperfused infarcts; (2) this accelerated process of necrosis lasts about 40 to 50 hours, a duration that is hardly influenced by infarct size; and (3) the reperfusion-induced acceleration of enzyme release resembles the reoxygenation-induced enzyme release from anoxic hearts.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative relationship between left ventricular function and serum cardiac myosin light chain I levels after coronary reperfusion in patients with acute myocardial infarction

To estimate the extent of myocardial infarction after coronary artery reperfusion, serum levels of cardiac myosin light chain (LC) I and creatine kinase (CK) were determined serially in 49 patients with acute myocardial infarction. Intracoronary thrombolysis was successful in 25 patients (reperfusion group), and 24 patients were treated in a conventional manner (control group). The peak level of CK appeared significantly earlier in the reperfusion group (11.3 +/- 3.1 hr, mean +/- SD) than in the control group (21.6 +/- 7.2 hr). Cumulative release of CK was significantly related to angiographically determined left ventricular ejection fraction 1 month after the attack in both groups (r = -.50; -.45, respectively). However, the amount of cumulative release of CK in the reperfusion group was greater compared with that in those with the same left ventricular ejection fraction in the control group. Peak appearance time of LCI was almost equal in the two groups (3.8 +/- 1.4 vs 3.9 +/- 1.2 days). Peak levels of LCI were related to the left ventricular ejection fraction in the reperfusion group (r = -.63) and in the control group (r = -.74), and the slopes of their regression lines were similar. The cardiac index obtained on the day of onset in the two groups was related to peak levels of LCI but not to total release of CK. These results suggest that serum levels of LCI reflect the changes in left ventricular function after acute myocardial infarction, regardless of the presence of coronary reperfusion. Thus, serial determinations of LCI in serum facilitate noninvasive assessment of the effects of intracoronary thrombolysis on infarct size.

Influence of reperfusion on serum concentrations of cytosolic creatine kinase and structural myosin light chains in acute myocardial infarction

The kinetics of cytosolic and structural marker protein release from myocardium were studied in 44 patients with acute myocardial infarction. After intracoronary infusion of streptokinase, there was early recanalization of the infarct-related artery in 8 patients and late recanalization in 18. In 18 patients the infarct-related artery remained occluded. Creatine kinase (CK) level peaked and normalized significantly earlier in patients with early reperfusion than in patients with late reperfusion, and in patients with late reperfusion earlier than in patients with permanent occlusion. Thus, the interval of absolute diagnostic sensitivity of CK depends on early infarct perfusion. In contrast, release of myosin light chains was not significantly changed by recanalization of the infarct-related artery compared with that in nonreperfused myocardial infarction. Thus, in patients with acute myocardial infarction, myosin light chains may be superior to CK as a diagnostic means and for estimation of infarct size.

Peak creatine kinase as a measure of effectiveness of thrombolytic therapy in acute myocardial infarction

As part of the National Heart, Lung, and Blood Institute multicenter Thrombolysis in Myocardial Infarction Trial, the time to peak plasma creatine kinase (CK) activity as a marker of reperfusion in 272 patients with validated acute myocardial infarction was analyzed. Patients were treated with either tissue-type plasminogen activator or streptokinase by intravenous administration. All patients underwent acute coronary angiography. The infarct-related artery was identified and thrombolytic therapy administered. Reperfusion at 90 minutes was documented by angiography. CK was determined before institution of therapy and every 4 hours thereafter for the first 24 hours. Patients were classified into 3 groups for comparative purposes: group 1--occlusion with no reperfusion (n = 119); group 2--occlusion with reperfusion (n = 98); and group 3--subtotal occlusion (n = 55). Early (within 4 hours after treatment) and late (more than 16 hours after treatment) peaking of CK differentiated patients with drug-induced perfusion from those without reperfusion. Although peak CK between 5 and 11 hours after drug treatment did suggest perfusion through the infarct-related artery, it did not differentiate between drug-induced and spontaneous reperfusion. Clinically, early peak CK is a useful noninvasive means of assessing coronary artery patency. However, in clinical trials assessing drug therapy, the use of peak CK may overestimate drug effectiveness by including patients with spontaneous reperfusion.

Effect of spontaneous reperfusion on myocardial infarct size

The effect of perfusion of the infarct artery on myocardial infarct size was studied in 39 patients who had not received interventive therapy. At predischarge coronary angiography, 19 patients had subtotal and 20 total occlusion of the infarct artery. The early ST-segment elevation recorded on a 12-lead electrocardiogram was used as an index of the amount of initially jeopardized myocardium. Infarct size was estimated by peak serum creatine kinase and, at discharge, by a QRS score, sigma Q and sigma R on a 12-lead electrocardiogram, and by radionuclide global and infarct segment left ventricular ejection fraction. Despite a similar degree of initial ischemia (sigma ST), infarct size was smaller in the 11 patients with anterior infarction and subtotal occlusion than in the 9 patients with anterior infarction and total occlusion when measured by peak serum creatine kinase (2114 +/- 1192 U/l vs. 3653 +/- 1059 U/l, p less than 0.02), QRS score (5.0 +/- 2.7 vs. 9.6 +/- 3.5, p less than 0.01), sigma Q (3.25 +/- 2.74 mV vs. 5.92 +/- 3.56 mV, p less than 0.10), sigma R (4.36 +/- 1.25 mV vs. 2.16 +/- 0.91 mV, p less than 0.001), global left ventricular ejection fraction (45.0 +/- 12.2% vs. 33.4 +/- 6.7%, p less than 0.05), and infarct segment ejection fraction (40.4 +/- 8.2% vs. 30.3 +/- 5.4%, p less than 0.05). In the inferior infarct patients, both the degree of initial ischemia and final infarct size were similar in the 8 patients with subtotal and in the 11 patients with total occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Value of admission electrocardiogram in predicting outcome of thrombolytic therapy in acute myocardial infarction. A randomized trial conducted by The Netherlands Interuniversity Cardiology Institute

To determine the value of the admission 12-lead electrocardiogram to predict infarct size limitation by thrombolytic therapy, data were analyzed in 488 of 533 patients with acute myocardial infarction (AMI) from a randomized multicenter study. All patients had typical electrocardiographic changes diagnostic for an AMI and were admitted within 4 hours after the onset of chest pain; 245 patients were allocated to thrombolytic treatment and 243 to conventional treatment. Cumulative 72-hour release into plasma of myocardial alpha-hydroxybutyrate dehydrogenase (HBDH) was used as a measure of infarct size. In general, the amount of infarct limitation due to thrombolytic therapy was proportional to the size of the area at risk. Patients with new Q waves, high QRS score and high ST-segment elevation or depression had the largest enzymatic infarct size in both treatment groups, irrespective of location of the AMI. Compared with conventionally treated patients, patients with anterior AMI treated with streptokinase had significant infarct size limitation (480 U/liter HBDH, 37%), and limitation was most prominent in those with Q waves (820 U/liter HBDH) or high ST elevation (750 U/liter HBDH). Infarct size limitation in inferior AMI was less impressive (330 U/liter HBDH, 33%) and patients with high ST-segment elevation (460 U/liter HBDH) or marked contralateral ST-segment depression (430 U/liter HBDH) had the most notable infarct limitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of early intracoronary streptokinase on infarct size estimated from cumulative enzyme release and on enzyme release rate: a randomized trial of 533 patients with acute myocardial infarction

The effects of early intracoronary streptokinase (SK) on enzymatic infarct size and rate of enzyme release were studied in a randomized multicenter trial. A total of 533 patients with acute myocardial infarction (AMI) were allocated to either the SK treatment group (n = 269) or the conventional (control) treatment group (n = 264). Enzymatic infarct size was represented by the cumulative quantity of alpha-hydroxybutyrate dehydrogenase (HBDH) released by the heart per liter of plasma in the first 72 hours. Rate of enzyme release was represented by the ratio of HBDH quantities released in 24 hours and 72 hours. On an "intention to treat" basis, the SK group had a smaller (by 30%; p = 0.0001) median enzymatic infarct size and a higher (by 35%; p = 0.0001) median rate of enzyme release than the control group. Limitation of infarct size was less apparent in patients treated with intracoronary SK only (25%) than in patients treated with intravenous plus intracoronary SK (34%). Compared to the control group, the enzyme release rate in patients treated with intracoronary SK only was slightly less (34%) than that in patients treated with intravenous plus intracoronary SK (38%). Patients with a patent infarct-related coronary artery at acute angiography had a median infarct size which was 55% (p = 0.0001) smaller than the median infarct size of the control group, and the median rate of enzyme release was 38% (p = 0.001) higher than the median release rate of the control group. Patients with successful recanalization during intracoronary SK infusion had a median infarct size which was 31% (p = 0.002) smaller than the median infarct size of the control group and a median rate of enzyme release which was 42% (p = 0.0001) higher than the median release rate of the control group. Patients with persistent coronary occlusion in spite of thrombolytic therapy had a median infarct size which was 11% (NS) higher than the median infarct size of the control group, although the median rate of enzyme release was still 23% (p = 0.02) higher than the median release rate of the control group. It is concluded that thrombolysis in the early phase of AMI limits infarct size and that intracoronary SK treatment itself accelerates the process of enzyme release from infarcted myocardium, independent of the angiographic result.

Early detection of myocardial reperfusion by assay of plasma MM-creatine kinase isoforms in dogs

To determine whether myocardial reperfusion can be detected promptly by changes in profiles of isoforms of MM-creatine kinase (CK) in plasma, coronary occlusion was induced in 30 conscious dogs and reperfusion was initiated after 1, 2, 3, or 4 hr in 21. The myocardial isoform of MM-CK, MMA, was quantified in serial plasma samples by chromatofocusing. Before coronary occlusion, MMA comprised 13 +/- 7% (SD) of the total CK activity in plasma. The percentage of MMA (MMA%) was elevated before reperfusion, but increased markedly and consistently to a peak of 52 +/- 13% (n = 21) between 30 min and 1 hr after the time of onset of reperfusion. The rate of increase in MMA% was significantly faster with reperfusion at 1 hr (1.44 +/- 0.42% min-1), 2 hr (1.28 +/- 0.45% min-1), or 3 hr (1.02 +/- 0.27% min-1) (p less than .001), but not with reperfusion at 4 hr (0.48 +/- 0.34% min-1) compared with the rate in nonreperfused control dogs (0.29 +/- 0.09% min-1). Furthermore, the rate of increase in MMA% was neither influenced by peak total CK activity (r = -.1) nor dependent on infarct size measured histochemically 24 hr after coronary occlusion (r = -.003). The time from coronary occlusion to the peak of MMA% was reduced by reperfusion at 1 to 3 hr compared with control, but this index was not identified as rapidly as the rate of increase in MMA%. Accordingly, characterization of the rate of increase in MMA% in plasma when reperfusion occurs early after the onset of myocardial infarction permits prompt, reliable, and noninvasive detection of myocardial reperfusion.

Reperfusion arrhythmias during coronary reperfusion therapy in man. Clinical and angiographic correlations

We hypothesized that patients suffering acute myocardial infarction who have reperfusion arrhythmias (RPA) during intracoronary streptokinase infusion (ICSK) would have different clinical and angiographic characteristics and a larger infarction size than those who achieved reperfusion without RPA. Of 35 patients who received intracoronary streptokinase, 27 had successful reperfusion documented by angiography. Successful reperfusion was accompanied by RPA in eight patients and no RPA in 19 patients. RPA included episodes of ventricular tachycardia in one, idioventricular rhythm in four, junctional bradycardia in one, or AV block in two patients which occurred at the time of reperfusion. Myocardial infarction size was calculated using creatine kinase-MB (CK-MB) isoenzyme time activity curves using standard methods. The mean CK-MB g equivalents (eq) for those with RPA was 71 +/- 25 (+/- 1 SD) and for those with no RPA was 45 +/- 24 (p less than .04). In patients with RPA, ejection fraction rose 5 +/- 14 percentage points before discharge, but fell 10 +/- 13 points in those with RPA (p less than .03). There was no difference between groups in total dose of streptokinase, final degree of stenosis of the affected vessel, reocclusion rate, or time from onset of symptoms to reperfusion. We conclude that patients suffering acute myocardial infarction who have RPA during ICSK in most cases have a larger infarction site or a more "stunned myocardium," as indicated by greater CK-MB release and fall in ejection fraction which is not due to increased time of ischemia.

The circumflex coronary artery occlusion canine model of sudden death: methodology and electrocardiographic observations

This study deals with a left circumflex coronary artery occlusion-reperfusion canine model of sudden death using multiple electrocardiographic leads to define a subgroup of animals at high risk of ventricular fibrillation. Occlusion was followed by ventricular fibrillation in 15 of 30 animals (50%). In the 15 dogs surviving 60 min postocclusion, reperfusion gave rise to ten cases of ventricular fibrillation (66.7%). Thus, the total incidence of occlusion-reperfusion ventricular fibrillation was 25 of 30 (83.3%). Electrocardiographic delta R% changes greater than or equal to 25% in leads 2 and 3 at both 3 and 5 min postocclusion predicted the occurrence of postocclusion ventricular fibrillation with 80% specificity and 56% sensitivity. However, ST segment elevation greater than or equal to 0.5 mV in the same leads at the same times predicted postocclusion ventricular fibrillation with 67% specificity and 100% sensitivity. When only dogs with ST segment elevation greater than or equal to 0.5 mV in leads 2 and 3 at both 3 and 5 min postocclusion were considered, ventricular fibrillation postocclusion was seen in 15 of 20 dogs (75%) and ventricular fibrillation after reperfusion occurred in four of the remaining five animals (80%). Thus, in the subgroup of animals presenting with ST segment elevation greater than or equal to 0.5 mV in leads 2 and 3 at both 3 and 5 min postocclusion, the overall incidence of occlusion-reperfusion ventricular fibrillation was 19 of 20 (95%). These data may be useful in studies aimed at testing the effectiveness of drugs or other interventions in a canine model of sudden death.

High dose intravenous streptokinase in acute myocardial infarction--short and long term prognosis

Streptokinase (1 million international units) was given intravenously over 30 or 60 minutes to 50 patients four hours or less after the onset of acute myocardial infarction. All were aged less than or equal to 70 years and had 4 mm or greater ST segment elevation in anterior or inferior leads. Rapid (mean 95 min) ST segment resolution, which was taken to indicate reperfusion of the myocardium, occurred in 36 (72%) patients. In these 36 the average time from onset of symptoms to peak creatine kinase, creatine kinase MB, and myoglobin was 9.45 hours, whereas it was 17 hours in the 14 patients in whom indirect criteria did not indicate reperfusion. Reperfusion arrhythmias were invariably present and ventricular tachycardia developed in five patients and ventricular fibrillation in two. The infarct related artery was seen to be open in 28 (70%) of the 40 patients who had delayed coronary arteriography. The frequency of patency in the infarct related artery was no different in patients given streptokinase less than 2 hours or between 2-4 hours from onset of symptoms nor did it differ when streptokinase was infused over 30 or 60 minutes. Mean left ventricular ejection fraction was 57% in those with a patient infarct related artery and 48% in those with an occluded vessel. Eight patients subsequently underwent elective percutaneous transluminal coronary angioplasty after successful thrombolysis and six had coronary artery bypass grafting. There were nine in-hospital reocclusions of the infarct related coronary arteries. Two bleeding episodes occurred; one required transfusion. Five of the 50 patients died in hospital. All of them had had an anterior myocardial infarction; four had bifascicular block and one had right bundle branch block. During follow up, four patients died, two suddenly and two from reinfarction. During follow up (mean 15 months) the frequency of reinfarction, dyspnoea, and angina was low and there was no difference in the proportions of patients returning to work between those with an open infarct related artery and those with a closed infarct related artery. Intravenous administration of high dose streptokinase to selected patients during the acute phase of myocardial infarction is a safe, effective, and practical method of thrombolysis. It must, however, be followed by coronary arteriography to select those patients in whom percutaneous transluminal coronary angioplasty or coronary artery bypass grafting will be helpful.

The effects of the rate of intravenous infusion of streptokinase and the duration of symptoms on the time interval to reperfusion in patients with acute myocardial infarction

We studied the influence of the following variables on the time interval from initiation of an intravenous infusion of 750,000 U of streptokinase until reperfusion (reperfusion time) in 140 consecutive patients with an evolving acute myocardial infarction: (1) the rate of infusion of streptokinase, (2) the duration of chest pain before initiation of treatment, (3) patient age, (4) patient sex, (5) location of infarction, (6) history of previous myocardial infarction, and (7) pretreatment pathologic Q waves. The time of reperfusion was recognized by clinical criteria that were completely concordant with the anatomic findings in all 119 patients in whom patency or occlusion of the artery of infarction was established at delayed angiography (n = 116) or at postmortem examination (n = 3). The mean reperfusion time for the 129 patients for whom data were available was 49 +/- 36 min. The reperfusion time was inversely related to the rate of infusion of streptokinase (r = .41, p less than .001), but this effect of infusion rate appeared to plateau at rates of greater than 500 U/kg/min. In the 64 patients receiving infusions at rates of 500 U/kg/min or less, the mean reperfusion time was 60 +/- 40 min, whereas in the 58 patients receiving the drug at rates greater than 500 U/kg/min it was 35 +/- 22 min (p less than .001). The duration of chest pain before treatment was the only other studied variable found to influence the reperfusion time, but only at infusion rates of less than 250 U/kg/min (r = .6, p less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

A randomized trial of intravenous and intracoronary streptokinase in patients with acute myocardial infarction

The clinical effects of intravenous streptokinase in patients with acute myocardial infarction were compared with those of intracoronary streptokinase in a randomized, prospective study. Comparisons were also made with a historical control group. Fifty patients were entered into the study at 2.4 +/- 1.2 hr after onset of pain, and 27 were assigned to intravenous and 23 to intracoronary therapy. The doses of streptokinase averaged 212,000 U ic and 845,000 U iv (0.75 X 10(6) U/5 hr, n = 14 or 10(6) U/1 hr, n = 13). Results of studies of the two intravenous dosage schedules were similar and so were combined. Streptokinase was administered at 2.8 +/- 1.0 hr after onset of pain in the intravenous and at 4.3 +/- 1.4 hr in the intracoronary drug group (p less than .001). Convalescent (day 10) radionuclide ejection fractions were 54 +/- 14% for the intravenous and 50 +/- 16% for the intracoronary drug group. Change in ejection fraction from day 1 to 10 tended to be greater after intravenous drug: 5.1% (p less than .08) vs 1.2% (NS). Semiquantitative regional wall motion indexes in the infarct zone showed significant and similar modest improvement from admission to day 10 in both groups (p less than .02). Accelerated enzyme-release kinetics were noted after both therapies. Times of peak enzyme levels for patients on intravenous and intracoronary drug were, respectively, 12.5 +/- 5.0 and 11.5 +/- 4.3 hr for creatine kinase MB isoenzyme and 31.7 +/- 11.8 and 28.1 +/- 12.7 hr for lactic dehydrogenase (LDH). Peak LDH-1 level was lower in patients receiving intravenous drug than in the historical control group (p less than .05). Electrocardiographically summed ST segments diminished rapidly after therapy in both groups; Q wave development was similar and overall R wave loss was equivalent and less extensive compared with in historical control subjects. Infarct pain requiring morphine was diminished similarly in both treatment groups. Incidence of early arrhythmias and heart failure also did not differ. Posttherapy ischemic events and early surgery tended to be more common in the intracoronary group and bleeding was more common in the intravenous group. Intravenous drug did not decrease early hospital mortality (intravenous drug = 5, historical control = 4, intracoronary drug = 1); the differences in this parameter among groups were not significant. At convalescent angiographic evaluation, anterograde perfusion was present in 73% of those receiving intravenous and 76% of those receiving intracoronary drug.(ABSTRACT TRUNCATED AT 400 WORDS)